Austin, Texas — With about 1 billion cars and light trucks on the road worldwide – and more than a quarter of them in the United States – more oil is consumed by internal-combustion engines used in transportation than in any other human activity. The private car itself is the most significant source of rising energy consumption for transportation.

"It's a different mind-set altogether," says Dale Bulla, a retired teacher in Austin, Texas, who has not bought a drop of gasoline since he purchased his Nissan Leaf in April. "[A] big weight is off me. I just don't have to think very much at all about oil or gasoline anymore. It feels good."

The mind-set is catching on. Global sales of plug-in vehicles are starting gradually, but expected rapid growth will push annual sales to 1.3 million vehicles by 2017, says John Gartner, an analyst with Pike Research in Boulder, Colo. He expects 2012 to be the first big year with a quarter million plug-in vehicles sold worldwide. At least a dozen new plug-in models from 10 automakers will hit showrooms in 2012.

Pumping a clean jobs agenda and greater energy independence, President Obama wants to put 1 million plug-in vehicles on US roads by 2015.

US plug-in sales will be just 61,000 next year, rising to 303,000 by 2017, according to Pike Research estimates. And Mr. Obama's goal, says Mr. Gartner, probably won't be achieved until 2016. Long-term growth projections by the Electric Power Research Institute (EPRI) suggest dramatic growth: 5.8 million plug-in vehicles on US roads by 2020. The Institute's "high" scenario shows those numbers could soar to 12 million by 2020 and 65 million by 2030.

While the status quo is still entrenched – 6 out of 10 Americans polled by USAToday/Gallup said they will not buy an all-electric car no matter how high gas prices go – Nissan executives were enthused about the 43 percent who would consider it.

As plug-ins hit the street, they provide glimmers of what a world without oil as a requirement for driving would be – from the quiet, peppy ride to the economics and public policy that might arise, say Gartner and other industry experts.

All-electric versions use no gasoline at all – while plug-in hybrid vehicles use battery power first and a tiny gas engine as a range extender. The coming plug-in wave portends a starkly different world, say their new owners and industry experts: No more obligatory, costly trips to fill up. No imported oil. No, or far fewer, tailpipe emissions. And for many plug-in owners – 30 percent of whom today already have solar panels on their garage rooftops to charge their vehicles' batteries – there are no emissions at all.

While some experts forecast 6 million to 12 million plug-in vehicles on US roads by 2020, that would still be just 3 to 4 percent of all cars on the road. But their presence could accelerate far more rapidly if oil prices soar, experts say.

"[We have] studies under way to see what we could do if we had to double production [or] triple production," Mr. Akerson said at the Volt's launch in late 2010. "I have a sense this is going to be a game changer. We have to be prepared to meet that."

Still, at this point, just 10,000 Americans have purchased an electric-drive plug-in vehicle – either a Nissan Leaf or a Chevrolet Volt, the only such vehicles currently available from major automakers. But that's not a reflection of demand: Both GM and Nissan have long waiting lists and are sold out this year – and maybe next, says Bradley Berman, editor of Plugincars.com.

The Leaf is a $35,200 all-electric vehicle (EV) that uses no gasoline. A charged battery takes it about 100 miles. The price of the Volt plug-in hybrid electric vehicle (PHEV) is $39,995. Its small gas engine recharges the battery if a 40-mile range is exceeded. Both qualify for a $7,500 federal tax break and lease for about $370 per month.

Mr. Bulla and his wife, Pat, who own two cars – a conventional gas-electric hybrid Toyota Prius and their Leaf – say the Leaf has changed their lives. Zipping around Austin to appointments and shopping, they almost always opt to drive the all-electric-powered car. The outlines of their post-oil world are vivid for them: Sailing past gas stations is great fun – and there's satisfaction that they're not contributing to the demand for oil from hostile countries, the Bullas say. Solar panels on their garage rooftop that charge the Leaf's battery provide another big benefit: no emissions at all. There's great relief that we are not contributing to global warming anymore with our driving, Mr. Bulla says.

At least four of the Bullas' neighbors are now among a few dozen in the Austin area who own Leafs. Word of mouth and taking a ride in a neighbor's electric car – or a rental, or taxi – are likely to be the best sales pitch, Mr. Bulla and experts say.

City planners are already anticipating a traffic jam of plug-ins and, from Seattle to Boston, are installing thousands of charging stations.

Perhaps nowhere would the driving landscape be more profoundly affected than here, deep in the heart of once oil-rich Texas, where the municipal utility Austin Energy this month will finish deploying more than 100 new charging stations to provide a quick top-off to EV batteries while drivers shop or work. Cost to the car owner: $2 an hour. (Charging at home is far cheaper. It would cost the Bullas about $2.22 for an eight-hour charge – 2.2 cents per mile for a full charge – if they used power from the grid.) The utility is not profiting much; it's just readying for the 36,000 vehicles it expects to plug in locally by 2020.

"We have only a handful of plug-ins now, but people want these cars and we have to know how to handle them, how they are going to fit into our system," says Shems Duval, head of Austin Energy's push to build charging stations across the city. "These charging stations are mostly a psychological support to drivers that lets them know they can get a charge if they need one."

But the municipal utility will profit if it can sell a lot of cheap wind power at night to charge those plug-in vehicles, she says. And car owners will save plenty: The EPRI study's "medium" scenario shows plug-ins would save 1.4 billion gallons of gasoline annually by 2020.

"It's probably still too early to think about a major transition away from the internal-combustion engine," says Mr. Berman. "But that doesn't mean there won't be a lot of drivers ... that will be fully satisfied without oil."

Gartner predicts a successful transition. Even so, he adds, "The entire market for electrified vehicles ... will still be less than 3 percent of the new vehicle fleet [in 2017]." Beyond early adopters, he says, will come "a more mass audience where folks are more sensitive to the cost of the vehicle, fuel savings, and monthly cost savings – something beyond the badge of saying 'I'm a sustainable driver.' "

David Tuttle likes being sustainable. But it's not the main reason the computer engineer drives an electric car. His Lexus has collected cobwebs in his Austin garage since the Chevrolet Volt he ordered last year arrived this spring. Now he drives up to 40 miles around town on his overnight charge before the car switches seamlessly to the gas engine.

But so far, he says, that's rarely happened: "It's been four months since I visited a gas station. There are all sorts of good uses for oil – but transportation isn't one of them. If more people bought electric vehicles we would import less oil, cut our trade deficit in half, and help our country."